I. Field of the Invention
The present invention relates to a process for producing hydroxyapatite fibers.
II. Description of the Related Art
Hydroxyapatite is the major inorganic component constituting hard tissues such as bones and teeth, and is one of the materials having excellent bio-compatibility. Therefore, hydroxyapatite is used as materials for artificial dental root and bone prosthesis, and plays an important role in the field of biological materials. In addition, research and development of hydroxyapatite for use in industrial fields as absorbents of chromatography, ion-exchangers, sensors, catalysts and the like are also now widely made.
Thus, applications of hydroxyapatite to various uses are expected. Since the performance of hydroxyapatite is largely influenced by the shape of the hydroxyapatite particles, it is thought that control of the shape of the hydroxyapatite particles is necessary. For example, in the field of biological materials, hydroxyapatite is demanded to have high strength, high toughness and low modulus of elasticity. In general, mechanical properties of ceramics and high polymers are effectively improved by incorporating a material in the form of needles or fibers. Especially, in cases where a material is used as a biological material, the material preferably has bio-compatibility and is in the form of atoxic needles or fibers. Therefore, it has been intensively studied to obtain hydroxyapatite having bio-compatibility and is in the form of atoxic needles or fibers. As a result, needle-shaped or fiber-shaped hydroxyapatite, Ca-deficient hydroxyapatite and CO.sub.3 -containing hydroxyapatite have been synthesized by various methods such as hydrothermal synthesis method, reflux method, agar gel method, alginate-spinning method and the like.
A process for producing needle-shaped or fiber-shaped hydroxyapatite, which is simpler than the known methods is demanded.